PDFBOX-5153: fix resulting position of findString

git-svn-id: https://svn.apache.org/repos/asf/pdfbox/trunk@1888460 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/pdfbox/src/main/java/org/apache/pdfbox/pdfparser/COSParser.java b/pdfbox/src/main/java/org/apache/pdfbox/pdfparser/COSParser.java
index eac16bb..ba20b01 100644
--- a/pdfbox/src/main/java/org/apache/pdfbox/pdfparser/COSParser.java
+++ b/pdfbox/src/main/java/org/apache/pdfbox/pdfparser/COSParser.java
@@ -2120,7 +2120,7 @@
             {
                 if (counter == 0)
                 {
-                    position = source.getPosition();
+                    position = source.getPosition() - 1;
                 }
                 counter++;
                 if (counter == stringLength)
@@ -2138,6 +2138,7 @@
         }
         return position;
     }
+
     /**
      * This will parse the trailer from the stream and add it to the state.
      *